The authoritative public forum
  for Metal Finishing since 1989
-----

Gold Plating on Top of Tin for Nickel Plated Copper Leadframes

I am need to plate Gold on top of Tin for an electronics application. The application is for a Nickel plated copper leadframe that must have Tin plating on one side for soldering purposes and areas of Gold plating for wirebonding on the other. My goal is to reduce cost by plating Tin over the whole lead frame, thus eliminating a masking step and then selectively plate Gold in the required areas. Currently the way I am going to do it is mask the areas separately, once for the Tin plating and another time for the Gold plating. If anyone has done something like this or knows someone who has, please let me know. Thank you

Tony Minervini
- Itasca, Illinois, USA
2000

Hello Tony,

One method I would like to suggest is selective,brush electroplating the gold on the specific areas after the tin plating the entire part. Selective areas of the lead frame can be nickel and gold plated over the tin. Depending on the plating area and the number of parts, brush plating may be a quick and easy solution to your problem.

If you would like further information please contact us at your convenience.

Chris Helwig
- Valencia, California
2000

---

2000

Dear Tony

I recommend you silver-gold alloy metals for your application. bondability is very excellent and tarnish resistance is also very good.

In semiconductor industry,this is one in applicable plating metals to alternate Sn/Pb.

In case of applying brush gold plating, thick and uneven thickness may be caused silver epoxy bleeding in die attach process.

Nelson NK Key
- Seoul, Korea

---

2000

In my experience, plating over tin can be problematic. I have had difficulty getting excellent adhesion over tin.

If you only mask the areas you need to apply gold and then brush plate the gold in the masked areas as suggested above by Chris Helwig you will cut your masking work in half and avoid adhesion problems.

Terry Collins
Gold Touch Inc.

Cleveland, Ohio